Preparation of 21-acyloxy-3, 17alpha-dihydroxy-5, 6-dichloro-20-ketopregnane



. mime- 2,786,856 PREPARATION OF 21-ACYLOXY-3,l7a-DIHY-DROXY-5,6-DICHLORO-2(l-KETOPREGNANE Frank A. Cutler and John M.Chemerda, Metuchen, N. J.,

assignors to Merck & Co., Inc., Railway, N. J., a corporation of NewJersey N Drawing. Application March 22, 1954, Serial No. 417,959 6Claims. (Cl. 260397.47)

This invention relates to novel steroid compounds and processes ofobtaining the same. More particularly, it is concerned With a processfor converting pregnenolone to A 3,20 diketo 1711,21 dihydroxy-pregneneand A 3,20 diketo 17a hydroxy-pregnene, and with novel steroid compoundsuseful in the preparation of these compounds.

This application is a continuation-in-part of our copending applicationSerial No. 326,576, filed December (EH33! =0 I --OH CHiORi I 0H 1 (VII)The discovery of the remarkable effectiveness of cortisone and similarrelated compounds in the treatment of various diseases has stimulatedgreat interest in finding other methods of preparing these compounds.

Itis an object of the present invention to provide a process for thepreparation of A 3, 2O diketo :,21- dihydroxy-pregnene (ReichsteinsSubstance S), an active adrenal hormone and A 3,20 diketo 17mhydroxypregnene. It is a further object to provide novel derivatives ofpregnenolone which are useful as intermediates in the synthesis of theseproducts. Another object is to provide processes for the preparation ofsaid intermediates. Other objects will be apparent from the detaileddescription of our invention hereinafter provided.

In accordance with the present invention, we have found that A 3, 20diketo l7a,21 dihydroxy-pregnene can be prepared from pregnenolone (A 3hydroxy- 20 keto pregnene) by a process which can be represented asfollows:

CH5 S =0 ?-OR1 RO & C1 G1 a 01 (I!) (III) CH: l (DH/50111 =0 0 ---OH I l0320B: CHnORg l 1 --OH ---OH CHiOH wherein R represents an acylsubstituent, and R1 and R2 represent lower aliphatic acid radicals.

In this process, an acyl derivative of pregnenolone (I) is firstchlorinated to saturate the A -unsaturated group and obtain thecorresponding dichloro derivative (11) which is then acylated to producethe corresponding A 20-enol acylate derivative (III). Upon reacting theenol acylate with an oxidizing agent the corresponding 17,20- epoxide'(IV) is obtained which on hydrolysis is converted to the 170: hydroxy20 keto compound (V). The latter compound is then reacted with bromineto produce the corresponding 2l-bromo compound (VI) which is convertedto the 2l-acyloxy compound (VII) by treatment with a salt of a loweraliphatic acid. Upon treating VII with an oxidizing agent thecorresponding 3- keto compound (VIII) is obtained which upon treatmentwith a dehalogenating agent forms the 2l-acylate of A 3,20 diketol7oc,2l dihydroxy pregnene (IX). Upon hydrolysis with alkali this esteris cleaved to produce Reichsteins Substance S (X).

Pregnenolone esters (inter alia., A 3 acetoxy 20- keto pregnene, A 3benzoxy 20 keto pregnene, A 3 propionoxy 20 keto pregnene, and thelike), employed as starting materials in the process of our invention,are readily prepared by acylating pregnenolone in accordance withprocedures known in the art. Although other pregnenolone esters aresuitable for use as starting materials in the process of our invention,we generally prefer to employ a lower aliphatic acid ester, such as theacetate, since these esters are readily and conveniently prepared.

The first step of our process comprising the formation" of the5,6-dichloro compound is readily efiected by treating the startingmaterial with chlorine. This is conveniently accomplished by intimatelycontacting the acylated pregnenolone derivative with chlorine in asuitable solvent medium, such as ether, benzene, halogenatedhydrocarbons, and the like. For the obtainment of maximum yields underoptimum conditions, we find it desirable to employ an amount of chlorinein slight excess over that theoretically required and to carry out thechlorination at a temperature below about C. Thus, the chlorination ofpregnenolone acetate is readily accomplished by mixing a chloroformsolution of pregnenolone acetate and pyridine with a carbontetrachloride solution of chlorine at a temperature of about C.

and allowing the resulting reaction mixture to warm up to about 15 C.Alternatively, the reaction can be carried out by passing chlorine intoa solution of the pregnenolone ester in a mixture of benzene andpyridine at room temperature. After completion of the reaction, thesolution is washed successively with dilute acid, dilute alkali andwater to remove the pyridine and the solvent is evaporated by warmingunder diminished pressure to obtain the 5,6- dichloro compound which canbe further purified by recrystallization from suitable solvents. Y

The second step of our process is effected byreacting the 5,6-dichlorocompound with an excess of lower aliphatic acid anhydride or a loweraliphatic acid halide in the presence of a catalytic amount of a strongacid. The

acylation is conveniently effected by heating the reactants at atemperature of about 601l0 C. for about one to six hours. Strong acids,such as concentrated sulfuric acid, benzene sulfonic acid, p-toluenesulfonic acid, and the like, are suitable catalysts for this reaction.For example, A -3,ZO-diacetoxy-S,6-dichloro-pregnene is convenientlyobtained by heating 3-acetoxy-5,6-dichloro- ZO-keto-pregnane with aceticanhydride in the presence of p-toluene sulfonic acid on a steam bath forabout four to five hours. After completion of the reaction, the productis recovered by decomposing the excess acetic anhydride with water,extracting the resulting aqueous solution with a suitable solvent suchas ether, benzene, chloroform, carbon tetrachloride, ethyl acetate andthe like, and evaporating the extracts.

The oxidation of the enol acylate (III) to the corresponding epoxycompound (IV) is effected by intimately contacting the enol acylate withan organic peroxy acid in a suitable solvent medium. Organic peroxyacids suitable as oxidizing agents for this reaction that might bementioned include performic acid, peracetic acid, perbenzoic acid,perphthalic acid, and the like. Solvents for the reactants, for example,benzene, ether, halogenated hydrocarbons, saturated hydrocarbons, andthe like, are suitable reaction mediums. Thus,3,20-diacetoxy-5,6-dichloro-17,20-epoxy-pregnane is prepared by adding abenzene solution of perbenzoic acid, or preferably an ethyl acetatesolution of perphthalic acid, to A -3,2O-diacetoxy-5,6dichloro-pregneneat a temperature of about 10 C., allowing the resulting reaction mixtureto warm up to room temperature, and permitting the reaction to continueat room temperature until the oxidation is substantially complete. Atthis point the mixture is washed with alkali to remove the excessperbenzoic acid, and the resulting benzene layer is evaporated underdiminished pressure to obtain the desired epoxy compound.

The hydrolysis of the epoxide (IV) to form the correspondingl7a-hydroxy-20-keto compound (V) is effected by treating IV with analkali or acid in an aqueous alcoholic medium. Alkalis such as alkalimetal hydroxides, carbonates and bicarbonates, and acids such as mineralacids, are suitable for effecting this hydrolysis. For example,3,l7a-dihydroxy5,6-dichloro-lO-keto-pregnane is produced bf adding asolution of 3,20-diacetoxy-5,6-di chloro-17,20-epoxy-pregnane in hotmethanol to a solution of potassium hydroxide in aqueous methanol andmaintaining the resulting reaction mixture at about 25 C. After thehydrolysis is completed by stirring the reaction mixture at roomtemperature for about an hour, the product is recovered by neutralizingthe reaction mixture with acetic acid, and evaporating the resultingneutralized solution during which process the product crystallizes.

The' conversion of V to the corresponding 21-bromo compoundis carriedout by adding a slight molar excess of bromine to the steroid dissolvedin a suitable inert organic solvent such as an ether, an aromatic oraliphatic hydrocarbon, a halogenated hydrocarbon, and the like at atemperature of about 25100 C. For example,3,17a-dihydroxy-5,6-dichloro-20-keto-2l-bromo-pregnane is obtained byadding a solution of bromine in chloroform to a chloroform solution of3,l7a-dihydroxy-5,6- dichloro-ZO-keto-pregnane and maintaining thereaction mixture at about 40-55 C. After completion of the reaction, thereaction mixture is washed with an aqueous solution of sodiumbicarbonate, and the product is obtained in crystalline form byevaporating the chloroform solution toa small volume.

The conversion of the 2l-bro1no compound (VI) to the 21-acyloxycompound(VII) can be accomplished by several methods. The reaction can becarried out by direct metathesis with an alkali metal salt of a loweraliphatic acid. This reaction is conveniently accomplished by heating asolution of the 21-bromo compound in a suitable solvent such as acetone,with the alkali metal salt for about 4-15 hours. The alkali metal saltcan be added to the reaction mixture directly or formed in situ by thereaction of equivalent amounts of the organic carboxylic acid and analkali metal hydroxide or carbonate.

Alternatively, the 2l-bromo compound can be first converted to the21-iodo compound by treatment with an iodide salt, for example sodiumiodide, and the resulting iodo compound converted by metathesis asdescribed above, to the desired 2l-acyloxy compound.

Further, as will be apparent to those skilled in the art, the 21-acyloxycompound is also conveniently obtained by reacting the iodide salt andthe alkali metal carboxylic acid salt concurrently with the 2l-bromocompound. This method is generally preferred in carrying out this stepof our process. Thus, 3,l7a-dihydroxy-5,6-dichloro-ZO-keto-Zl-acetoxy-pregnane is conveniently prepared by '5 refluxing amixture of 3,17u-dihydroxy-i6-dicliloro-20- keto-Zl-bromo-pregnane,acetone, potassium acetate, acetic acid and sodium iodide 1' 2r about 45hours. After adding water to the resulting reaction mixture, anddistilling off the acetone, the desired 2l-acetoxy compound can berecovered in crystalline form.

The oxidation of the B-hydroxyl group of compound VII to the 3-ketogroup of VIII is effected by treatment with suitable strong oxidizingagents. This reaction is most conveniently effected by treatment withchromium trioxide in an aqueous solution of acetic and sulfuric acids ata temperature of about 20C. For example, 3,20 dilteto 5,6 dichlorol7m-hydroxy-2l-acetoxypregnane is obtained by intimately contacting3,17a-dlhydroxy-5,6-dichloro-20-ketc-2lacetoxy pregnane with chromiumtrioxide in an acetic acid-sulfuric acid reaction medium. The recoveryof the oxidized product is effected by extraction of the product fromthe reaction mixture with a suitable solvent such as chloroform, carbontetrachloride, benzene and the like.

The removal of chlorine from Compound VIII to pro duce thecorresponding. ester of A -3,20-diketo-l7a,2ldihydroxy-pregnene iseffected by treating VIII with a dehalogenating agent. Thus, thisdehalogenation is readily accomplished by heating VIII with Zinc orchrornous chloride. For example, A-3,20-diketo-l7oc-hydroxy-2lacetoxy-pregnene is produced by intimatelycontacting 3,20 diketo-5,6-dichloro.-l7a-hydroxy2l-acetoxypregnane withzinc in an acetic acid medium at a temperature of about 4080C. After thereaction is complete, the reaction mixture is filtered and the desiredproduct is recovered incrystalline form by adding water to the resultingfiltrate and cooling the. aqueous solution.

The esters of A -3,20-diketo-l7a,2l-dihydroxy-pregnene so obtained canbe hydrolyzed by treatment with alkali to obtain Reichsteins SubstanceS.

In accordance with a further embodiment of the present invention, itsisfound that A -3,2O-diketo-l7a-hydroxy-pregnene is produced byox-idizing3'-hydroxy-5,6- dichloro-l7a-hydroxy-20-keto-pregnane to obtain thecorresponding 3-keto compound, and dehalogenating the latter compound.This process can be shown as follows:

(XII) The oxidation of V to obtain the 3-keto compound is effected byreacting V with a strong oxidizing agent. Thus, this reaction isconveniently efiected by reacting 3-hydroxy-5,6-dichloro-17d-hydroxy 20keto pregnane with chromium trioxide in the presence of acetic acid andsulfuric acid. The 3-keto compound is recovered by adding water to thereaction mixture, extracting the resulting aqueous solution with asuitable solvent such as chloroform, and exaporating the solventextracts.

The dehalogenation of XI to produce A -3,20-diketo l7u-hydroxy-pregnenecan be accomplished as described above for converting Compound VIII toCompound IX. Thus, the reaction is effected by treating 3,20-diketo-5,6-dichloro-l7a-hydroxy-pregnane in acetone solution with chrornouschloride. The dehalogenated product is recovered in crystalline form byconcentrating the resulting reaction mixture under diminished pressureuntil the product precipitates and filtering the resulting concentrate.

In the step of removing the chloro substituents from3,20-diketo-5,6-dichloro-l7u,2l-dihydroxy-pregnane and3,20-diketo-5,6-dichloro-l7a-hydroxy-pregnane, the initial reactionproduct is believed to be the A compound which readily isomerizes toform the corresponding A compound. This isomerization is convenientlyeffected by treating the reaction product with a small amount of an acidsuch as sulfuric acid.

The products, A -3,20-diketo-l7a,2l-dihydroxy-pregnene, the esters of A-3,20-diketo-l7a-,2l-dihydroxypregnene, and A-3,20-diketo-l7a-hydroxy-pregnene which are obtained in accordance withthe processes of the present invention can be treated by microbiologicalfermentation processes to introduce an oxygen contain ing substituent atC-ll. Thus, these compounds are useful intermediates in the preparationof cortisone, and hydrocortisone, and similar related compounds.

It was indeed unexpected to find that the 5,6-double bond could beprotected by the addition of chlorine in the process of our invention.Other attempts to protect this double bond by the addition of hydrogenchloride or the addition of bromine were unsuccessful. The addition ofHCl caused some epimerization at C-l7, and the derivative so obtainedwould have eliminated hydrogen chloride under the reaction conditions ofour process. Similarly, when the double bond is protected by theaddition of bromine, the dibromo derivative of the pregnenolone ester isalso unsatisfactory for use in the process of our invention. The dibromoderivative loses hydrogen bromide under, the conditions of enolacylation. Also the dibromide was not suitable for use in the latersteps of our process.

The following examples serve to. illustrate methods of carrying out theprocesses of the present invention.

EXAMPLE 1 3-acet0xy-5,6-dichIOro-ZO-ketO-pregnane The starting material,pregnenolone acetate, may be conveniently prepared from pregnenolone asfollows: A suspension of pregnenolone g.) in acetic anhydride (333 ml.)was heated to reflux, the solid all dissolving. The solution wasrefluxed 3.5 hours and then chilled slowly, with seeding, finallychilling in ice. The crystals of pregnenolone acetate were collected,washed with cold methanol and dried at room temperature.

Pregnenolone acetate (152 g., 0.425 mole) was dissolved in chloroform(1500 ml.) and cooled to 20C. A solution of chlorine in chloroform wasprepared by passing chlorine gas into chloroform and on titrationiodimetrically against thiosulfate was found to be 0.689 M. A 650 ml.portion (l.05 0.425 mole) was added rapidly (a few minutes) to thesteroid solution, maintaining the temperature below 20C. The solutionwas then concentrated under reduced pressure with a minimum of heat,flushed with acetone, and, pumped dry. The residue was crystallized bydissolving in 800 ml. of boiling acetone, chilling, filtering, andwashing with cold acetone. 'After drying to constant weight on thefunnel, the product, 3-acetoxy-5,6-dichloro-20-keto-pregnane, melted atl94-l96.6C.

The product may be recrystallized from methanol. The pure compoundmelted at 196.6-198 C. The rotation was +6.5 (C=l, chloroform).

7 EXAMPLE 2 3-acetoxy-5,6-dichloro-20-keto-pregnane To a solution of 25g. of pregnenolone acetate in 940 ml. of chlorform was added 6 ml. ofpyridine. The solution, protected from atmospheric moisture by dryingtubes, was cooled to -60 C. and 79 cc. of a 0.93 M solution of chlorinein carbon tetrachloride was added with stirring. A precipitate (complexof pyridine and chlorine) formed. The mixture was allowed towarm to 15C. with stirring and with dissolution of the precipitate to give acolorless solution. The solution was washed successively with ex cessdilute hydrochloric acid, water, aqueous sodium bicarbonate and finallywater. The solution was dried and concentrated and the residue wasflushed with acetone and recrystallized from acetone to yield3-acetcxy-5,6-dichloro-20-keto-pregnane melting at l93197 C.

EXAMPLE 3 A -3,20-diacetoxy-5,6-diclzloro-pregnene A solution of 3acetoxy-5,6-dichloro-20-keto-pregnane (106.25 g., 0.248 mole) andp-toluene sulfonic acid monohydrate (14.16 g, 0.0745 mole) in aceticanhydride (558 ml.) was heated on the steam bath for 4.5 hours. Thebrown solution was cooled to C. and water (2235 ml.) at 10 C. was addedrapidly to hydrolyze the excess acetic 'anhydride. The mixture wasagitated and the temperature was kept below 30 C. by occasional cooling.A granular solid separated after about minutes. After another 15 minutesthe mixture was extracted with ether (3 X400 ml.). The combined etherextracts were washed with water (3x800 ml.), 10% sodium carbonatesolution (2X 320 ml.) and water (3X800 ml.). The ether solution wasdried over sodium sulfate and concentrated under reduced pressure. Theresidue was flushed with benzene and the solvent removed underdiminished pressure to obtain A -3,20-diacetoxy5,6- dichloro-pregnenewhich was used directly in the next step.

EXAMPLE 4 3,20-diacet0xy-5,6-dichloro-I 7,20-epoxy-pregnane To the A-3,20-diacetoxy-5,6-dichloro-pregnene (0.248 mole) was added 9 10 ml.(1.5 0.248 moles) of perbenzoic acid in benzene solution at 10 C. Thesolution was allowed to warm to room temperature and was titratedperiodically. After 4.75 hours 88% of the theoretical amount ofperbenzoic acid was consumed. The solution was washed free of'perbenzoicacid with cold. 0.5 N sodium hydroxide (3 l000 ml.), to neutrality withwater (3X1000 ml.), was dried over sodium sulfate and concentrated todryness under reduced pressure. The amorphous residue was flushed withmethanol, becoming crystalline. This residue was boiled with methanol(120 ml.) but did not dissolve. The suspension was chilled and filtered,and the crystalline product, 3,20-diacetoxy 5,6d-ichloro-l7,20-epoxy-pregnane, was washed wtih cold methanol and dried.

EXAMPLE 5 3,2 O-diacet0xy-5 ,6-dich low-17,20-epoxy-pregnane To 0.139gram-mole of A -3,20-diacetoxy-5,6-di chlororegnene (previously flushedwith ethyl acetate) was added 600 ml. of a 0.487 molar solution ofmonoperphthalic acid in ethyl acetate (cold). The solid rapidlydissolved and the solution warmed itself to 30 C. The reaction waslargely complete in three hours but was allowed to stand 25 days. Thesolution was washed free of peracid with cold 0.5 N sodium hydroxide (3X600 ml.) and to neutrality with water (3 X600 ml), was dried oversodium sulfate and concentrated to dryness under reduced pressure. Theresidue was slurried with boiling methanol (70 ml.) and then chilled andfiltered. The crystals-were washed with cold methanol 8 and dried,yielding 3,20-diacetoxy-5,6-dichloro-17,20- epoxy-pregnane. EXAMPLE 63,1 7a-dihydroxy-5,6-dichl0r0-20-ket0-pregnane A solution of potassiumhydroxide (96.3 g., 1.72 moles) in water (180 ml.) plus methanol (717ml.) was prepared and cooled to 25 C. A solution of3,20-diacetoxy-5,6-dichloro-17,20-epoxy-pregnane (84 g., 0.172 mole) inboiling methanol (1000 ml) was added over fifteen minutes, maintainingthe temperature at 25 C. with an ice bath. The reaction was stirred foran hour at room temperature, during which time a small amount of productprecipitated. The mixture was neutralized with acetic acid (84 ml.) andconcentrated to a small volume under reduced pressure. Water (717 ml.)was added and after chilling, the crystals of 3,17u-dihydroxy-5,6-d-ichloro20-keto-pregnane were collected, washed three times withwater, and dried. The product melted at 194494.8" C. dec. Uponrecrystallization the product was found to melt at 203204 C. dec.

EXAMPLE 7 3,17a-dihydr0xy-5,6-dichl0r020-ket0-pregnane Five grams of3,ZO-diacetoxy-5,6-dichloro-17,20-epoxypregnane obtained in Example 5was dissolved in boiling methanol (202 ml.). A solution of potassiumbicarbonate (6.15 g.) in water (20.2 ml.) was added and the mixture wasrefluxed for three hours. Water was added, and the methanol was removedunder reduced pressure, crystallization occurring in the process. Theresulting aqueous suspension was chilled and filtered, and the crystalswere washed with water and dried to give 3,17a-dihydroxy-5,6-dichloro-20-keto-pregnane, melting at 192-196 C. (dec.).

EXAMPLE 8 3,1 7a-dihydr0xy-5,6-dichl0r0-20-ket0-21-br0m0-pregnane3,17a-dihydroxy 5,6 dichloro-ZO-keto-pregnane (4.03 g., 10 mM.) wasdissolved in warm chloroform ml.). A solution of bromine (11 mM.) inchloroform (28.1 ml. total volume) was added over a period of one hourmaintaining the reaction at 4648 C. The solution was Washed with 10%sodium bicarbonate solution (50 ml.) and water (50 ml.). The chloroformsolution was concentrated under reduced pressure and the residue becamecrystalline on warming in a small amount of methanol. After chilling,the crystals of 3,17a-dihydroxy- 5,6-dichloro-20-keto-2l-bromo-pregnanewere collected, washed with a little cold methanol, and dried. Theproduct melted with decomposition at 179.5-181.5 C.

EXAMPLE 9 3,1 7a-dihydr0xy-5,6-dichl0ro-20-ket0-21- acetoxy-pregnaneEXAMPLE 10 3,1 7oc-dihydr0xy-5,6-dichlor0-20-keto-2I- acetoxy-pregnane Amixture of 0.32 g. of 3,17u-dihydroxy-5,6-dichloro-20-keto-21-brom0-pregnane, 1.0 g. of potassium acetate and 25 'cc. ofacetone was refluxed for four hours. Water (50 ml.) was added and theacetone was removed under reduced pressure. Theresulting crystallinesuspension was chilled and filteredand the crystals. were washed withwater and dried. When dry the: product melted at 188-192 C. (dec.). Itsinfrared spectrum was the same as that of an authentic specimen: of3,170;- dihydroxy-5,6-dichloro-20-keto-2l-acetoxy-pregnane;

EXAMPLE ll 3 ,ZO-diketo-S ,6 -dichlr0-1 7a-hydr0xy-2I acetoxy-pregnaneOne gram of 3,17a-dihydroxy-5,6-dichloro--keto-21- acetoxy-pregnane wasdissolved in acetic acid (20 ml.) and water (2 ml.) was added to preventfreezing. The solution was chilled in an ice bath. A solution ofchromium trioxide (0.216 g.) in water (0.2 ml.) plus acetic acid (2.5ml.) was added over ten minutes while stirring in the ice bath. Sulfuricacid (cone, 0.121 ml.) was then added over two minutes as stirringcontinued, in the ice bath. After 20 minutes a heavy precipitate hadformed. After 70 minutes further, the mixture was shaken with chloroform(50 ml.), and water (50 ml.) The chloroform layer was washed with 2.5%sodium bicarbonate solution (3X50 ml.) and water (50 ml.), with backwashing with small amounts of chloroform. The chloroform solution wasdried over sodium sulfate and concentrated under reduced pressure. Thecrystalline residue, 3,20 diketo5,6-dichloro-17a-hydr0xy-21-acetoxy-pregnane, was washed onto a funnelwith anhydrous ether. The white fibers of3,20diketo-5,6-dichloro-17ahydroxy 21 acetoxy-pregnane decomposed at198- 198.5 C.

EXAMPLE 12 A -3,20-diketo-1 7a-hydroxy-2l -acetoxy-pregnene 0.5 g. of3,20-diketo-5,6-dich1oro-17a-hydroxy-21-acetoxy-pregnane was dissolvedin warm acetic acid ml.) and with stirring was treated over a period ofone hour with zinc dust in five portions of 0.1 g. each at progressivelyincreasing temperatures beginning at C. and ending at C. The mixture wasfiltered and the cake was washed with acetic acid (10 ml.). The filtrateplus wash was diluted slowly with water ml.) and the suspension waschilled for two hours and filtered. The crystals of A-3,20-diketo-17a-hydroxy-2l-acetoxy-pregnene (Substance S acetate) werewashed with water, dried, and recrystallized from acetone.

EXAMPLE 13 A -3,20-diket0-1 7ot-hydroxy-21 -acetoxy-pregnene A solutionof chromous chloride was prepared by treating a solution of chromicchloride (10 g.) in water (40 ml.) containing concentrated hydrochloricacid (4 ml.) with amalgamated zinc dust (20 g.). The solution ofchromous chloride was added to a solution of 3,20- diketo 5,6 dichloro17a-hydroxy-21-acetoxy-pregnane (0.50 g.) in acetone (70 ml.) under acarbon dioxide atmosphere. After a few minutes standing at roomtemperature crystallization occurred. After an hour water was added andthe acetone was removed under reduced pressure. The resulting suspensionof crystals was chilled and the crystals were collected, washed withwater and dried, giving material melting at 218-225 C. This materialshowed A max. at 2410 with E% of 267, indicating that about 60% of the A-3,20-diketo-17a-hydroxy- ZI-acetoXy-pregnene had already beenisomerized to Substance S acetate. Complete isomerization was effectedby adding to a hot solution of 0.100 g. of the material in acetone (5ml.) 6 drops of a solution prepared from 0.3 ml. of concentratedsulfuric acid and 10 ml. of acetone. The solution was boiled for sixminutes then cooled and the resulting crystals of Substance S acetatewere separated. After drying, the product melted at 234-236 C., showedmax. at 2400 A. (E%=4l9) and its infrared spectrum was identical withthe infrared spectrum of an authentic specimen of Substance S acetate.

I0 EXAMPLE 1-4- 3,20-diketo=5,6-dichlbr0-1 7 a-hydroxy-pregnane Tengrams of 3-hydroxy-5,6-dichloro-17a-hydroxy-20- keto-pregnane wasdissolved in glacial acetic acid (3.50 ml.). Water (35 ml.) was addedand the solution was cooled to 4 C. A solution of'2.48 g. of chromiumtrioxide in 2.48 ml. of water and 22 ml. of acetic acid was added overfour minutes with stirring and in an icebath. Concentrated sulfuric acid(1.4- ml.) was. added over five minutes. and then the. reaction mixture.was stirred further in the ice bath for 100. minutes. The mixture. wasthen shaken with chloroform (437 ml.) and water (700 ml.). The aqueouslayer was separated and reextracted with chloroform (100 ml.). Thecombined chloroform layer was washed with water (500 ml.), 2.5% aqueoussodium bicarbonate solution (2X 500 ml.) and water (500 ml.). Thechloroform solution was dried with sodium sulfate and concentrated underreduced pressure with a minimum of heat. The residue was slurried withether, filtered, washed with ether and dried. The 170:-hydroxy-S,6-dichloro-3,ZO-diketo-pregnane so obtained decomposed at -160C.

EXAMPLE l5 A -3,20-diket0-1 7uz-hydr0xy-pregnene To a solution of 6.13g. of 17a-hydroxy-5,6-dichloro- 3,20-diketo-pregnane (prepared as inExample 14) in acetone (800 ml.) was added 500 ml. of chromous chlorideprepared as described in Example 13. The solution was concentrated underreduced pressure and the resulting suspension of crystals was chilledand filtered and the product was washed with water. When dry it meltedat -205 C.

To a solution of 4.43 g. of the above material in acetone (100 ml.) atthe boiling point was added 5.31 ml. of a solution of concentratedsulfuric acid (0.3 ml.) in acetone (10 ml.). The solution was boiled sixminutes, 60 ml. of acetone distilling ofi in the process. The solutionwas chilled and the resulting crystals of 17a-hydroxyprogesterone werecollected, washed with cold acetone and dried. The product, A*-3,20-diketo-l7u-hydroxypregnene, melted at 210-215 C.

EXAMPLE 16 3 acetoxy 5,6 dichloro 17a hydroxy 20 keropregnane A mixtureof 5.00 g. of 3,20-diacetoxy-5,6-dichl0ro- 17,20-epoxy pregnane, 30 cc.of methanol and 0.1 cc. of concentrated aqueous hydrochloric acidsolution was prepared and heated at reflux temperature for a period ofapproximately 30 minutes. The mixture was then chilled in an ice bathand the resulting crystals of 3-acetoxy-5,6-

; dichloro-17a-hydroxy-20-keto-pregnane were filtered and washed withcold methanol. The crystalline product was then dried and recrystallizedfrom acetone to give essentially pure3-acetoxy-5,6-dichloro-l7a-hydroxy-20-ketopregnane, M. P. 211-218 C.dec.

Various changes and modifications may be made in carrying out thepresent invention without departing from the spirit and scope thereof.Insofar as these changes and modifications are within the purview of theannexed claims, they are to be considered as part of our invention.

We claim:

1. The process which comprises intimately contacting3,17a-dihydroxy-5,6-dichloro-ZO-keto-pregnane with bromine to producethe corresponding 21-bromo compound, and reacting said bromo compoundwith an alkali metal salt of a lower fatty acid to produce thecorresponding 21-acyloxy compound.

2. The process which comprises intimately cont-acting3,17a-dihydroxy-5,6-dichloro-ZO-keto-pregnane with bromine to produce3,17a-dihydroxy-5,6-dichl0ro-20-keto- 11 21-bromo-pregnane, and reactingsaid bromo compound with potassium acetate and sodium iodide to produce3,17 0z dihydroxy 5,6 dichloro 2O keto 21- acetoxy-pregniane.

3. The process which comprises intimately contacting3,1711-dihydroxy-5,6-dich1oro20-keto-pregnane with bromine to produce3,17oc-dihYdIOXY-S,6-diCh101'O-20-k6t0- 21-bromo-pregnane.

4. The process which comprises reacting3,17a-dihydroxy-S,6-dich1oro-20-keto-2l-bromo-pregnane with an alkalimetal salt of a lower fatty acid to produce the corresponding 21-acyloxycompound.

12 5(The process which comprises reacting3,17a-dihydroxy-S,6-dich1oro-20-keto-2l-bromo-pregnane with potassiurn'acetateand sodium iodide to produce3,17a-dihydroxy-S,6-dich1oro-20-keto-2l-acetoxy-pregnane.

6. 3,17 dihydroxy 5,6 dichloro 2O keto 21- bromo-pregnane.

References Cited in the file of this patent Heer: Helv. Chim. Acta 34,359-72 (1951).

1. THE PROCESS WHICH COMPRISES INTIMATELY CONTACTING3,17A-DIHYDROXY-5,6-DICHLORO-20-KETO-PREGNANE WITH BROMINE TO PRODUCETHE CORRESPONDING 21-BROMO COMPOUND, AND REACTING SAID BROMO COMPOUNDWITH AN ALKALI METAL SALT OF A LOWER FATTY ACID TO PRODUCE THECORRESPONDING 21-ACYLOXY COMPOUND.